1. Field of the Invention
The present invention relates in general to a caption display of a video cassette recorder, referred to hereinafter as VCR and more particularly to a caption display apparatus for a VCR which is capable of storing caption display signals in a memory and outputting the stored caption display signals to a screen to display them in any operating modes of the VCR under selection of the user.
2. Description of the Prior Art
FIG. 1 illustrates block diagram of a conventional caption display apparatus for a VCR. As shown in this drawing, the conventional caption display apparatus for the VCR comprises a video signal processing circuit 10 for receiving a video signal, processing luminance and chrominance signals of the inputted video signal and correcting vertical and horizontal synchronous signals of the inputted video signal, a caption signal detection circuit 20 for detecting a caption signal from the processed video signal from the video signal processing circuit 10, a caption display signal generation circuit 30 for generating a caption character signal in response to the detected caption signal from the caption signal detection circuit 20 and then outputting a caption display signal as a result of determination of a display size and a display window position of the generated caption character signal, a caption display control switch 40 for transferring the caption display signal from the caption display signal generation circuit 30 in only a normal play mode, and a video/character signal combination circuit 50 for combining the caption display signal transferred in only the normal play mode by the caption display control switch with the processed video signal from the video signal processing circuit 10 and outputting the combined signals to a monitor 60 so that the caption display is performed on a video picture on a screen of the monitor 60.
The video signal processing circuit 10 includes a luminance/chrominance processor 11, a buffer 12 and a synchronous corrector 13 and the caption signal detection circuit 20 includes a low pass filter 21, a video buffer 22, a line selector 23 and a data slicer and synchronous separator circuit 24. Also, the caption display signal generation circuit 30 includes a character generator 31, a character memory 32 and a display controller 33.
The operation of the conventional VCR caption display apparatus with the above-mentioned construction will now be described.
In operation, upon receiving the video signal on which the caption signal is carried, the video signal processing circuit 10 processes the luminance and chrominance signals of the inputted video signal and corrects the vertical and horizontal synchronous signals of the inputted video signal. In other words, in the video signal processing circuit 10, the luminance and chrominance signals of the inputted video signal are processed by the luminance/chrominance processor 11 and the vertical and horizontal synchronous signals of the inputted video signal are corrected by the synchronous corrector 13. Also in the buffer 12, noise of the inputted video signal is removed. The processed video signal from the video signal processing circuit 10 is applied to the caption signal detection circuit 20 and the video/character signal combination circuit 50. It is noted herein that the caption signal is carried in a predetermined interval (equalizing pulse interval) of a vertical blanking interval of the processed video signal from the video signal processing circuit 10.
In the caption signal detection circuit 20, the processed video signal from the video signal processing circuit 10 is low pass-filtered by the low pass filter 21 and then buffered by the video buffer 22, which applies the buffered video signal to the data slicer and synchronous separator circuit 24. Also, the line selector 23 generates a line select signal for designation of the interval of the video signal in which the caption signal is carried. The generated line select signal from the line selector 23 is also applied to the data slicer and synchronous separator circuit 24.
Then in the data slicer and synchronous separator circuit 24, from the video signal is sliced the caption signal which is carried in the predetermined interval (equalizing pulse interval) of the vertical blanking interval of the video signal, and the vertical and horizontal synchronous signals are separated from the video signal. As a result, the resulting caption signal is detected from the video signal in the data slicer and synchronous separator circuit 24.
Upon detection of the caption signal, the caption display signal generation circuit 30 generates the caption character signal in response to the detected caption signal and then outputs the caption display signal as a result of determination of the display size and the display window position of the generated caption character signal. Namely, in the caption display signal generation circuit 30, the character generator 31 addresses the character memory 32 according to the detected caption signal. As a result, the caption character signal is generated from the addressed location of the character memory 32. Then, the size and the window position when the generated caption character signal is displayed are determined under the control of the display controller 33. As a result of the determination of the display size and the display window position of the generated caption character signal, the caption display signal is outputted from the display controller 33.
The caption display signal from the display controller 33 is transferred to the video/character signal combination circuit 50 in only the normal play mode by the caption display control switch 40. The caption display control switch 40 is turned off in only the normal play mode under control of a controller (not shown), in order to transfer the caption display signal from the display controller 33 to the video/character signal combination circuit 50 in only the normal play mode. On the other hand, the caption display control switch 40 is turned on in modes (for example, Slow, Still, Cue, REV. and etc.) other than the normal play mode under the control of the controller, so that the caption display signal from the display controller 33 is bypassed to ground. As a result, in this case, the caption display signal from the display controller 33 is not transferred to but blocked from the video/character signal combination circuit 50.
In the normal play mode, the caption display signal from the display controller 33 is combined in the video/character signal combination circuit 50 with the processed video signal from the video signal processing circuit 10. The combined signals from the video/character signal combination circuit 50 are outputted to the monitor 60. For this reason, the caption display is performed on the video picture on the screen of the monitor 60 in only the normal play mode.
However, the conventional VCR caption display apparatus has a disadvantage, in that the caption display is not performed in the modes other than the normal play mode such as, for example, Slow, Still, Cue, REV. and etc., since it is adapted to be performed in only the normal mode.